docs: def decode_aes256_plain_auto(data, encryption_key):
      """Guesses AES cipher (EBC or CBD) from the length of the plain data."""
      assert isinstance(data, bytes)
      length = len(data)
  
      if length == 0:
          return b''
      elif data[0] == b'!'[0] and length % 16 == 1 and length > 32:
          return decode_aes256_cbc_plain(data, encryption_key)
      else:
          return decode_aes256_ecb_plain(data, encryption_key)